1. Field of the Invention
The present invention relates to a wind powered turbine of the vertical-axis type for use in large configurations.
In particular, the invention herein contemplates the provision of a self-starting, free-standing, vertical-axis type rotor which employs both fixed and pivoted airfoil blades, assembled on a triangular rotor frame. The angle of attack of the pivoted blades is monitored and controlled in reference to the prevailing winds for improved aerodynamic efficiency. RPM control and arrest of operation by aerodynamic means is also provided by a controller operating the pivoted blades, permitting the turbine to operate in very high wind speeds. The rotor base teminates on a ring shaped tower mounted on guiding wheels, disposed in a circular pattern on pillars. The revolving ring shaped tower base, forms the armature of an energy converter by electromagnetic induction, allowing the rotary energy to be harnassed directly, at ground level on a stationary installation thereby limiting the weight to be carried by the rotating turbine.
2. Prior Art
The Darrieus rotor under development by the National Research Council in Canada and Sandia Laboratories in the U.S.A. is a vertical-axis rotor employing airfoil blades bent into a catenary shape and using electric motors or Savonious rotor starting. While simple, the prior methods lack versatility and aerodynamic efficiency. The feasibility of scaling-up to super giant turbines is not possible with known types of vertical-axis turbines.
The Gironmill concept employing symetrical blades of constant chord, which are flipped from a positive to a negative orientation at diametrically opposite points, requires strong winds to start, is difficult to operate at constant RPM and is less efficient than the Darrieus rotor. Giromills do not permit scaling-up to large individual installations.
The Vortex-turbine concept is a complex structure, which requires considerable amounts of material and labor, offers an enormous impact surface of the wind forces and could therefore prove relatively vulnerable and uneconomical.
The propeller, is a horizontal-axis device of good aerodynamic efficiency, but it requires a tall tower and orientation into the wind, consequently, it is not comparatively feasible for large scale energy conversion.